The present invention relates to a valve driving control apparatus for driving intake and exhaust valves for an internal combustion engine, more particularly to a valve driving apparatus for an internal combustion engine which comprises a plurality of power cylinders each having a plurality of intake and exhaust reciprocating valves.
The applicant of the present invention has already proposed a valve driving system for providing an efficient drivability over the whole range of the rotational speed i.e., high to low of the engine, in which each of the power cylinders is equipped with a plurality of intake and exhaust valves, where in at least one of the intake valves and at least of the exhaust valves are switched either operative or inoperative depending upon the load conditions of the engine.
In such a valve driving system as mentioned above, in which the change-over operation of the operative or inoperative state of the valve is performed at a predetermined rotational speed of the engine, especially when the engine has been driven near the above-stated predetermined rotational speed, such a switching operation occurs so frequently. As a result, the control part of the valve driving mechanism will be gradually deteriorated and which may cause the production of unpleasant noises. Furthermore, comfortableness of the motor vehicle which is powered by this type of internal combustion engine may be deteriorated by the output fluctuation due to a difference of outputs before and after the switching of the valve operation. In addition, there was a defect that the engine power reduces at the rotating speed at which the above-described switching operation of the valves is performed.